With the development in the miniaturization and complex functionality of electronic devices in recent years, the power supplied to the electronic devices shall be operated in the high-frequency area. Accordingly, noise control and source-voltage smoothing are required, and consequently, the functions performed by the capacitor in the electronic circuit are becoming more and more important in electronic componentry. There is a high demand for solid electrolyte condensers that are more compact and have greater electrostatic capacitance and excellent frequency characteristics providing low impedance.
Generally, the impedance of a condenser in a low frequency range depends on the electrostatic capacitance and the equivalent series resistance (ESR), wherein the frequency of the low frequency range is lower than the self-resonant frequency at which the ESR is equivalent to the resistance. Moreover, in the high frequency range having a frequency higher than the self-resonant frequency, the impedance is increased due to the equivalent series inductance or lead inductance (ESL) effect. In this case, ESR plays a more important role than ESL in the impedance characteristics of the solid electrolyte condenser; therefore, by seeking to decrease the ESR in the solid electrolyte condenser it is feasible to efficiently and effectively decrease the resistance.
To reduce the ESR in the solid electrolyte condenser, one solution employed is to connect two condenser components in parallel in a package. Using this solution, a greater electrostatic capacitance is obtained while reducing the ESR. The solid electrolyte condensers disclosed in Patent Literature 1 and Patent Literature 2 are examples of solid electrolyte condensers using this solution.
Patent Literature 1 discloses an example of a solid electrolyte condenser, in which two capacitor components are laterally connected in parallel at one side of the cathode terminal. The anode terminal of the solid electrolyte condenser as a single lead frame, when viewed from said lateral direction, has a -shape formed by bending processing, and is formed by making the portion of the anode wire, that is connected to the capacitor components, to have a greater width. Moreover, the anode wire is disposed eccentrically in said lateral direction relative to the center of the condenser component. In this way, when using resistance spot welding to connect the anode wire to the anode terminal, a wider space between the two welded portions (anode wire and anode terminal) is provided to avoid the defective welding of each welded portion, and to achieve a sufficient welding strength. However, in the solid electrolyte condenser, in order to reduce the ESR, the condenser component should be made into a planar shape in order to ensure a sufficient connecting area of the cathode terminal with respect to the condenser component. Such configuration of the condenser component may result in the increased size of the package.
Patent Literature 2 discloses an example of a solid electrolyte condenser, in which two condenser components are connected in parallel in the longitudinal direction at two sides of the cathode terminal. The anode terminal of the solid electrolyte condenser is formed by anode wire fixed at a pair of spacers at the two sides and is connected with the anode wire of the condenser component at each spacer. In this configuration, as compared with the solid electrolyte condenser disclosed in Patent Literature 1 discussed above, the condenser component is made into a planar shape, a sufficient connecting area of the cathode terminal with respect to the condenser component is ensured without any increase in size, and hence, it is feasible to reduce the ESR. However, when fixing the pair of spacers at the anode terminal, each spacer is fixed by resistance spot welding. Therefore, the increased amount of welding reduces manufacturing efficiency. Welding spots in close proximity to one another also causes deficient welding and welding strength degradation. These problems have already been disclosed in Patent Literature 1. Moreover, according to Patent Literature 2, regarding the two alternative processes of forming the pair of spacers and the anode terminal as a whole, or omitting the spacer and shaping the front end portion of the anode terminal as a spacer, either option involves a complicated bending process, which is problematic.